Only HDMI is connected.
xrandr says :
Code:
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 1920 x 1920
VGA_1 disconnected (normal left inverted right x axis y axis)
_PanningArea:
_OutputNumber: 1 (0x00000001)
ConnectorNumber: 1 (0x00000001)
ConnectorType: VGA
SignalFormat: VGA
supported: VGA
DVI-D_1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 1600mm x 900mm
_HDMI: 1 (0x00000001) range: (0,1)
_Coherent: 0 (0x00000000) range: (0,1)
_Backlight: 8645728 (0x0083ec60) range: (0,255)
_PanningArea:
_OutputNumber: 2 (0x00000002)
ConnectorNumber: 2 (0x00000002)
ConnectorType: DVI-D
SignalFormat: TMDS
supported: TMDS
1920x1080 60.0 *+
1680x1050 60.0
1400x1050 60.0
1280x1024 59.9 60.0
1440x900 60.2
1280x960 60.0
1280x800 60.0
1280x768 60.0
1280x720 60.0
1152x768 54.8
1024x768 60.0
800x600 60.3 56.2
640x480 60.0 59.9
I've no doubt that this TV can handle 1920x1080 'cause PS3 users play blueray @1080p on it (even if Sony says rez is limited to 1360x768).
By the way, I'm unable to have more than 800x600, so 1360x768 is far far away 
Still trying ...
Any way, this is to be a HDTV related problem, not driver one.
Or something is wrong between PC and HDTV ... Who said "You !" ? 
Note : NVidia users are able to display 1080p by deactivating some validation modes, but it's another story.